The present invention relates generally to agricultural implements and, more particularly, to a steering system for an agricultural implement, such as a towed planter, that can automatically steer the implement during field operations or road transport.
Conventional agricultural implements are designed to follow the motion of a towing vehicle, such as a tractor. In this regard, most agricultural implements are passively steered principally by the tractor rather than have their own steering mechanisms. However, increasingly, there is a desire for implements that are capable of limited self-steering. That is, in some situations, it may be desirable for the implement to be steered so as to maintain alignment with the tractor when the tractor is moving across a sloped area or avoiding an obstruction, such as a mailbox.
A number of steering systems have been developed as an aftermarket add-on to make a non-steerable implement steerable. One such system is GPS-based that is mounted to the toolbar of the non-steerable implement. Such add-on systems generally have two subsystems: the steering subsystem that mechanically causes steering of the implement and the auto-guidance subsystem (GPS, for example) that controls the steering subsystem. These subsystems can be quite costly and ultimately cost prohibitive. For example, it is not uncommon for the steering subsystem alone to cost several thousands of dollars with additional costly expense for the auto-guidance subsystem. Also, after market systems are design to provide implement steering during field operation and do not provide steering function while transporting. Additionally, for many aftermarket add-on systems, the implement must be mechanically modified, which may not be practical for some types of implements, such as folding planters, or negate warranties for the implement.
Moreover, steerable implements have been limited heretofore in the type of available movements. For example, many steerable implements have systems that are designed to maintain alignment of the implement with the tractor. While there is a need in some circumstances to maintain such alignment, a steerable implement that can be steered intentionally along an offset track may be desirable in other circumstances, such as during transport. Additionally, it is desirable to have an implement that can be automatically controlled to turn or otherwise corner during field operations. Automatic implement swath tracking during field operation would also be desirable.